The 1927 Nobel Prize in Physiology or Medicine went to an Austrian doctor with an unusual obsession. Julius Wagner-Jauregg had been treating bouts of dementia in people with advanced syphilis by injecting them with blood from a malaria patient. The induced malarial fevers, he reported in 1917, curbed their dementia.For centuries medicine has flirted with the notion that heat — whether produced by fever, heat lamps, or a warm bath — can treat mental illness. Since Wagner-Jauregg’s ethically fraught work, the idea has fallen out of favor, and “fever therapies” have, understandably, failed to catch on.But the idea has returned in a new clinical trial suggesting that the spa-like experience of lying back while your body is heated for an hour or two acts as a mood enhancer — one that’s powerful enough to rapidly curb symptoms of depression.“Hyperthermia made people feel immediately happy — excited, happy, energetic,” lead researcher Charles Raison, a professor of psychiatry at the University of Wisconsin-Madison, told BuzzFeed News. “I think it provides an explanation for why sweat lodges evolved so many times across history.”Some 16 million adults in the U.S. have depression, but antidepressant drugs don’t work for many and come with a variety of side effects. So the hunt for alternatives or complements to drug-based treatments, particularly those that work quickly, is on in earnest.Earlier this week, for example, a team from Imperial College London reported that psilocybin, the hallucinogenic compound in magic mushrooms, improved the symptoms of 12 people with depression when conventional medicines had failed to work.The new hyperthermia study included 30 people with mild depression. About half the group went through a body-warming treatment that elevated their body temperature to about 101.3 degrees Fahrenheit for a little over an hour using infrared lights and heating coils placed a few feet away. The other group went through a procedure that was staged to look similar, but didn’t heat their bodies as much.After that single session, the volunteers returned to the lab for weekly psychiatric evaluations for six weeks. Both groups saw a mild improvement in their depression symptoms. But only those who had the full hyperthermia saw their improved moods last through that period. This group scored at least five points lower than the control group each week on the Hamilton Rating Scale, a questionnaire-based evaluation that reflects the severity of depression symptoms.“It’s a good proof-of-concept randomized control trial,” Noah Philip, assistant professor of psychiatry and human behavior at Brown University and the Providence VA Medical Center, told BuzzFeed News. The results, he said, “give the green light that we are looking at a relevant mechanism.”But he cautioned that the trial only included people with mild depression, who may be more likely to respond to the heat treatment than those with a more severe form of the illness. “It’s easier to get there,” he said.“I think it’s innovative. I think it’s not a crazy idea — it’s not the final word, obviously,” David Avery, professor emeritus at the University of Washington School of Medicine, told BuzzFeed News. “If the data accumulates and it’s approved by the Food and Drug Administration as a medical device,” he added, “I think patients would be willing to try this treatment.”The study researchers were inspired by reports from oncologists who used intense heat as one of the treatments for their patients’ cancers. Even if their cancer didn’t shrink, the heat treatment improved their moods, those reports found.Others are investigating why some children with autism seem to show improved social and communication abilities when they have fevers brought on by colds. Research on this so-called “fever effect” is still in its infancy, and scientists don’t know why heat treatments may have such pronounced effects on the brain. But studies in mice and rats may provide some clues.For example, a team at the University of Colorado at Boulder that is studying rats warmed with heat say they see responses in the serotonin pathways of the brain, similar to those brought on by antidepressant drugs.“We know there are some thermosensitive pathways that go through the spinal cord and we’re asking in great detail which are those pathways,” Christopher Lowry, an associate professor of integrative physiology at the University of Colorado Boulder who also collaborated on the new study, told BuzzFeed News.In future studies, Janssen and Raison plan to investigate whether successive heat sessions have a better effect. They also want to try it in people with post-traumatic stress disorder, many of whom also experience depression.